Thanks Ottery. That is roughly how I translated it (with only O level Welsh some 50 years ago). I'm not sure I would have capitalised Taff's Well, as the Welsh version I saw didn't have 'fynnon' capitalised. It might have intended the source of the Taff rather than the village/town of that name.
I'd also have had problems with "soon Will the hour be striking noon" for "Mae’n awyr yn un o’r gloch", and for "Even now 'tis time for tea," as a translation of "mae wedi amser te,"